1. Field of the Invention
The present invention relates to a position detecting device for detecting the position of a movable unit relative to the position of a hold unit using a magnetic field generator and a magnetic field sensor, and relates to a method of adjusting the position of the magnetic field generator.
2. Description of the Related Art
Conventionally, it is known that an anti-shaking apparatus is often provided in a photographing device such as a camera. The anti-shaking apparatus moves an imaging sensor or a correcting lens in a plane which is perpendicular to the optical axis, by an amount corresponding to the hand-shake amount, so as to reduce the image blur in the image-forming plane.
U.S. patent application publication NO. 2005/0190267 discloses an anti-shaking apparatus which has a movable unit having an imaging sensor, and a hold unit which movably holds the movable unit. In this apparatus, the movable unit includes a hall element and a coil, and the hold unit includes a magnet.
The movable unit is moved together with the imaging sensor by the coil and the magnet, according to the hand-shake amount, in order to reduce the image blur in the imaging sensor. The hall element detects the position of the movable unit based on the magnetic flux density generated by the magnet. Due to this detection, because the position of the movable unit is known, the movable unit is moved to the correct position to reduce the image blur.
It is preferable that the hall element faces the center of the magnet in order to maximize the detection capability of the hall element when the movable unit is arranged in a standard position.
Generally, when the anti-shaking apparatus is assembled, the movable unit and the hold unit are built into one body unit after the hall element and the magnet are mounted on the movable unit and the hold unit, respectively. However, when the movable unit and the hold unit are built into one body unit, it is difficult to dispose the hall element so that it faces the center position of the magnet, particularly in the case where two or more two hall elements are provided in the movable unit.